Self-adjusting track circuits



March 11, 1969 F. H. WINKS ET 3,432,653

SELF-ADJUSTING TRACK CIRCUITS Filed July 14. 1966 I0 I a A '8 II Af+ l5I I v u l l PRIOR ART k FIG. 1

RELAY 22 I5 L 3 I f j I J FIG. 2 INVENTORS FRED H. wmxs HENRY e. WANSERATTORNEY United States Patent 2 Claims ABSTRACT OF THE DISCLOSURE Ourinvention relates to track circuits and more specifically to aself-adjusting track circuit which will compensate for track currentlosses due to moisture causing a current leakage or current seepage fromrail to rail.

The track circuits in use in railroading are extremely important anddelicate devices that control the movement of trains, provide for timeschedules and protect the lives of the passengers. The failure of evenone signal can cause either a stoppage of the train or a seriousaccident. Present day track signal circuits have been perfected tofunction well under normal conditions but these same circuits are unableto cope with the adverse conditions of moisture in the trackway. Theseadverse conditions can substantially prevent the power supply from everreaching the signal controlling relay. In fact, a substantial loss ofcurrent seepage across the tracks is the equivalent of a train axle onthe tracks and causes the relay to function as if a train were actuallyon the rails. In addition, even though the power source or supply maynot be completely shunted, enough moisture may be present to cause acurrent leakage or seepage which will drain the power supply to thepoint where it could not function properly on the relay.

It is necessary during adverse moisture conditions to adjust theelements of the track circuit to compensate for current seepage loss andthen during dry conditions to readjust the elements for normal usage.Thus costly manhours of labor are consumed in providing and keeping thetrack circuits in proper operating conditions.

Therefore an object of the present invention is to form a track circuitwhich is self-adjusting to all moisture and weather conditions so as toprovide a substantially cOnstant supply of electric power to the trackrelay.

A further object is to provide a track circuit with a means forcompensating for the loss of current due to seepage across the rails sothat the correct amount of current is provided to the relay so that itcan function properly.

Another object is to provide a track circuit with an additionalautomatic variable source of electric current which suppliessubstantially the same amount of current to the track relay as is lostby current leakage or seepage across the rails with the track sectionunoccupied.

We accomplish these and other objects by providing in the track circuitan additional source of current, one terminal of which is connected toone track rail and the other terminal to an electric conductor, either awire, cable, strip or piece of rail and placing the wire, cable, stripor piece of rail between and approximately parallel to the track rails,and having the additional source of current in the same phase as themain source of current so that if moisture in the trackway shunts outthe main current, the same moisture will cause the current in the wire,cable, strip or piece of rail to pass to the other rail, thusestablishing a secondary source of power and providing current tocompensate for the current seepage loss in the primary circuit.

For further comprehension of the invention and of the 3,432,653 PatentedMar. 11, 1969 objects and advantages thereof, reference will be had tothe following description, the accompanying drawing and to the appendedclaims in which the various novel features of the invention are moreparticularly set forth.

In the drawing, FIG. 1 is a schematic sketch of a normal present daytrack relay circuit and FIG. 2 is a similar type sketch of the circuitshown in FIG. 1, but with the additional elements and circuit providingleakage and seepage protection.

In the drawing and in the specification, in which like numerals indicatesimilar elements, the present day track circuit 10 -(see FIG. 1) isshown comprised of a circuit section A having a power source 11,resistance 12 and fuse 13 connected in series, as shown, to track rails14 and 15. It should be noted that rail 15 is insulated and is notelectrically continuous while track rail 14 is electrically continuous.Also a part of section A and connected in series to track rails 14 and15 is a fuse 16, a resistance 17 and one coil 18 of a transformer. Thetrack circuit 10 is also provided with circuit section B, which iscomprised of the other coil 19 of the transformer, a power source 20 anda signal operating relay 21, all connected in series. As is normal, thepower source 20 is much smaller than and of an opposing polarity to thepower source 11. Thus normally, the power source 11 prevails over thepower source 20 and holds the relay in a position showing a clear track.However, when a train axle is across the rails, it acts as a shunt tothe power source 11 and power source 20 then functions on the relay 21and causes it to move the signal to a position which indicates a trainis on the track.

As all the elements heretofore shown and numbered in FIG. 1 are againshown in FIG. 2, they need not be repeated and their existence will beassumed in FIG. 2. The new elements (see FIG. 2) that provide protectionagainst current leakage and current seepage loss comprise an opencircuit C extending from track 15 through a fuse 22, a resistance 23 anda power source 24, all in series, to the end of a wire, cable, strip,piece of rail or other elongated conductor 25. The conductor 25 ispositioned between the rails 14 and 15 with its elongated axis alignedwith the rails 14 and 15 and is of substantial length to allow ampleleakage or seepage of current across to rails 14 and 15. In fact, shouldphysical conditions warrant conductor 25 could be as long as rail 15.Conductor 25 should not be insulated and should be positioned along theroadbed in an exposed manner so that moisture which can cause electricalseepage from one rail to the other of the current from power source 11will equally well cause a current from power source 24 to pass fromconductor 25 across to rails 14 and 15. The power source 24 is in phasewith the power source 11 and must be large enough to completely takeover the function of source 11 when necessitated by trackway conditions.For best results circuit C should be joined to circuit section A in thevicinity of rail 15 and fuse 13, as is shown in the drawing (FIG. 2).

Although we have shown the invention in only its main form it should beunderstood that other combinations of electrical units not shown ordescribed may be used to form circuits different from that hereindisclosed but which circuits will embody the basic principles and ideasherein set forth. Therefore, we do not wish to limit ourselves to theprecise circuit herein disclosed, and we therefore reserve the right toall changes and modifications of the invention coming within the scopeof the invention.

Having thus described our invention, what we claim as new and desire tosecure by United States Letters Patent is:

1. In a track circuit for vehicles having dominating AC power source anda pair of track rails capable of acting as conductors to form a maincircuit, an additional AC power source and a noninsulated conductor,said additional AC power source being in phase with the first AC powersource and connected to one rail and to the conductor and the conductorbeing positioned between the rails, said additional AC power sourceadding to the total power available to cause the power to remainapproximately constant irrespective of the seepage loss across thetrack, a. signal circuit having a third AC power source of subordinatecharacter connected to said main circuit through a transformer wherebythe signal will be operative only when the main circuit is completelyshunted by an axle of a vehicle.

2. A track circuit as defined in claim 1, and said conductor being of anelongated shape and substantially parallel with the rails, and beingelectrically insulated at its ends and said additional power sourcebeing connected to said insulated rail.

References Cited UNITED STATES PATENTS 1,687,124 10/1928 Gilson.

2,089,836 8/1937 Martin.

FOREIGN PATENTS 289,537 4/ 1928 Great Britain.

DRAYTON E. HOFFMAN, Primary Examiner.

